Proposed Adjustments to PI-RADS Version 2 Decision Rules: Impact on Prostate Cancer Detection

Abstract

Purpose To test the impact of existing Prostate Imaging Reporting and Data System (PI-RADS) version 2 (V2) decision rules, as well as of proposed adjustments to these decision rules, on detection of Gleason score (GS) 7 or greater (GS ≥7) prostate cancer. Materials and Methods Two radiologists independently provided PI-RADS V2 scores for the dominant lesion on 343 prostate magnetic resonance (MR) examinations. Diagnostic performance for GS ≥7 tumor was assessed by using MR imaging-ultrasonography fusion-targeted biopsy as the reference. The impact of existing PI-RADS V2 decision rules, as well as a series of exploratory proposed adjustments, on the frequency of GS ≥7 tumor detection, was evaluated. Results A total of 210 lesions were benign, 43 were GS 6, and 90 were GS ≥7. Lesions were GS ≥7 in 0%-4.1% of PI-RADS categories 1 and 2, 11.4%-27.1% of PI-RADS category 3, 44.4%-49.3% of PI-RADS category 4, and 72.1%-73.7% of PI-RADS category 5 lesions. PI-RADS category 4 or greater had sensitivity of 78.9%-87.8% and specificity of 75.5%-79.1 for detecting GS ≥7 tumor. The frequency of GS ≥7 tumor for existing PI-RADS V2 decision rules was 30.0%-33.3% in peripheral zone (PZ) lesions upgraded from category 3 to 4 based on dynamic contrast enhancement (DCE) score of positive; 50.0%-66.7% in transition zone (TZ) lesions upgraded from category 3 to 4 based on diffusion-weighted imaging (DWI) score of 5; and 71.7%-72.7% of lesions in both zones upgraded from category 4 to 5 based on size of 15 mm or greater. The frequency of GS ≥7 tumor for proposed adjustments to the decision rules was 30.0%-60.0% for TZ lesions upgraded from category 3 to 4 based on DWI score of 4; 33.3%-57.1% for TZ lesions upgraded from category 3 to 4 based on DCE score of positive when incorporating new criteria (unencapsulated sheetlike enhancement) for DCE score of positive in TZ; and 56.4%-61.9% for lesions in both zones upgraded from category 4 to 5 based on size of 10-14 mm. Other proposed adjustments yielded GS ≥7 tumor in less than 15% of cases for one or more readers. Conclusion Existing PI-RADS V2 decision rules exhibited reasonable performance in detecting GS ≥7 tumor. Several proposed adjustments to the criteria (in TZ, upgrading category 3 to 4 based on DWI score of 4 or modified DCE score of positive; in PZ or TZ, upgrading category 4 to 5 based on size of 10-14 mm) may also have value for this purpose. RSNA, 2016 Online supplemental material is available for this article.

Population net benefit of prostate MRI with high spatiotemporal resolution contrast‐enhanced imaging: A decision curve analysis

“…High‐grade cancer was defined as presence of Gleason ≥3 + 4 adenocarcinoma. Both studies were also performed at large academic institutions using 3 T prostate MRI; the details of these studies are included in Table …”

“…Therefore, a threshold of PI‐RADS ≥3 using noncontrast sequences for performing biopsy yielded sensitivity and specificity of 97.8% and 51.6%, respectively, for detecting HGPCA. A threshold of PI‐RADS ≥4 using GRASP‐DCE for detection of HGPCA provided sensitivity and specificity of 87.8% and 79.1%, respectively, for HGPCA …”

“…Both studies were also performed at large academic institutions using 3 T prostate MRI; the details of these studies are included in Table 1. 23,24 The first study applied data from a cohort of 343 patients with 343 lesions from 2013-2015 using MRI with GRASP DCE-MRI, with MRI-ultrasound fusion biopsy serving as the reference standard. 24 All patients in this study were referred for prostate MRI to localize suspicious lesions before all biopsies with MRI-ultrasound fusion biopsy: factors such as patient and physician preference, MR imaging findings, clinical risk factors including family history, prior biopsy results, DRE findings, PSA level, and other serum and urine biomarkers indicated the need for testing.…”

“…23,24 The first study applied data from a cohort of 343 patients with 343 lesions from 2013-2015 using MRI with GRASP DCE-MRI, with MRI-ultrasound fusion biopsy serving as the reference standard. 24 All patients in this study were referred for prostate MRI to localize suspicious lesions before all biopsies with MRI-ultrasound fusion biopsy: factors such as patient and physician preference, MR imaging findings, clinical risk factors including family history, prior biopsy results, DRE findings, PSA level, and other serum and urine biomarkers indicated the need for testing. This study had two reviewers who evaluated all lesions; the interpretation results of reader 1 were used for the purposes of the present study given reporting of separate reader statistics and this reader's more established clinical experience with prostate MRI.…”

“…A threshold of PI-RADS ≥4 using GRASP-DCE for detection of HGPCA provided sensitivity and specificity of 87.8% and 79.1%, respectively, for HGPCA. 24 The second study involved 163 patients with 651 lesions from 2012-2015, and used standard DCE-MRI techniques, with prostatectomy as the reference standard. 23 Cases were consecutive patients who had undergone MRI before prostatectomy, while controls were consecutive patients who had no lesions on MRI and a negative biopsy.…”